The deamination of aromatic amines is a procedure of wide application in the chemical industry. While a variety of deamination techniques are known, deamination of aromatic primary amines customarily entails activation of the primary amino group by diazotization, followed by replacement of the diazo group with hydrogen. The conversion is conveniently effected by a "one-port", "one-step" reaction, wherein the primary amine is deaminated by reaction with a source of nitrous acid such as an alkyl nitrite, in the presence of an appropriate hydrogen donor, usually a solvent such as tetrahydrofuran or dioxane, as described, for example, by Cadogan et al (J. C. S. Perkins I, 1973, 541-542); Doyle et al (J. Org. Chem. 43: 4120-25, 1979); or Doyle et al (J. Org. Chem 42: 3494-98, 1977). The reaction broadly involves diazotization of the aromatic amine with decomposition of the diazonium salt to an intermediate aryl radical, which accepts hydrogen from the donor according to the following scheme: ##STR1## More classically, deamination is accomplished by a "one-pot," "two-step" textbook reaction, wherein the aromatic amine is first diazotized (usually by sodium nitrite in a mineral acid), and the diazo group subsequently replaced by hydrogen by reaction of the diazonium salt (generally termed "reduction" in the art) with an appropriate hydrogen donor such as alkaline formaldehyde, ethanol or hypophosphorous acid according to the following exemplary scheme: ##STR2## (see e.g., Brewster et al, JACS 61:2418-9, 1939). Simple diazonium salts may also be converted to more complex intermediate salts such as the diazonium fluoborates or fluorophosphates to improve stability and efficiency of the subsequent replacement reaction, as described, for example, in J. Org. Chem. 28:568-571, 1963 or JACS 74:6297-6298, 1952.
While these known techniques are generally effective in accomplishing the desired deamination, the reactions usually require several hours for completion, with frequently low yields. Further, the yields vary drastically and unpredictably with a number of parameters, particularly the types of hydrogen donors employed, and especially the number and type of substituents present on the aromatic moiety. It is accordingly desirable to provide an improved method for deaminating aromatic amines which is simple, versatile, reliable and rapid.